For this explore we mixed, heated, and reacted various substances to observe chemical reactions. The following balanced equations represent the eleven reactions that took place.
1. 4Fe+3O2= 2Fe2O2
2. CaO+ H20= Ca(OH)2
3. 2H2O2 (MnO2) = 2H2O + O2
4. 2NaHCO3 = H2O + Na2CO3 + CO2
5. Ca+2H2O = H2 + Ca(OH)2
6. Zn+ Pb(NO3)2 = Pb + Zn(NO3)2
7. 2Na2CO3+ 2Ba(NO3)2 = 4Na(NO3) + 2BaCO3
8. Pb(NO3)2 + 2KI = 2KNO3 + PbI2
9. CaCO3 + 2HCL = CO2 + H2O+ CaCl2
10. CH4 + 2O2 = CO2 + 2H2O
11. 4C2H5O2 +9O2 = 8O2 + 10H2O
One can tell that a chemical reaction took place by a change in temperature, color, or if it fizzes to produce a gas. For example, in the CaO+ H20= Ca(OH)2 reaction, the mixture fizzed when we added the H20 to the CaO. We also added a green solution to the mixture, and the top half turned blue, indicating that it was a base. For reaction number 10, CH4 + 2O2 = CO2 + 2H2O, their was a change in temperature because it created a flame.
As you can see above, the reactions are separated into sections. Section 1 is reactions that produce a single compound. For example, CaO + H2O = Ca(OH)2. Section 2 is reactions that start with a single reactant and result in multiple products. So, 2H2O = 2H2O +O2. In section 3, the single element becomes part of the compound, and part of the compound becomes a single element. This is like Ca + 2H2O = H2 + Ca(OH)2. In Section 4, there are 2 reactants and 2 products, all are compounds. The elements in the reactant compounds flip-flop as they become the product compounds. This looks like Pb(NO3)2 + 2KI = 2KNO3 + PbI2. Finally, in Section 5 the reactions produce CO2 and H2O. For example, CH4 + 2O2 = CO2 + 2H2O. These unique traits allow the chemical reactions to be categorized. So, you can make a unique model for each reaction, because all the reactions follow a specific “blue print” or layout. If you know what “model” or “layout” of the chemical reaction, then you can predict the outcome. For example, in our experiment, if you knew that the reaction followed the layout of the reactions in Section 5, then you could predict that the products would be CO2 and H2O.
Sources: Class experiment, notes, and discussion